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Bill Harris

First Video (FPV) Gear

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My first questions, since answered:

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Now that I have a couple quadcopter builds behind me (a 330-size and a 500-size) I'm working on my first FPV-capable aircraft.

This new quad will be based on a TBS Discovery airfame running four 2216 90kV motors on 4S. It will be designed for still photography of architecture, landscapes and property surveys and will be equipped with a pitch-only camera mount to aim a compact digital camera. The Pilot's camera/FPV camera will be mounted on the camera mount and be used for aiming and composition of the photo camera. OSD will be by EzOSD.

The flight radio will be UHF at 433 mHz. ((EzUHF module on a JR 8103 Tx and an 8-ch EzUHF Rx). Most of the time I'll be flying this aircraft LOS, but I will be using it for R&D of FPV systems.

Here are my questions:

What frequency will I need to use? I may retrofit FPV to my older Quads running with the usual 2.4gHz radios, so I'll want to avoid that video band. 1.2-1.3 gHz is available and works well for long-range work, but might be overkill for my initial LOS work. 5.8 gHz might be a good choice, and several systems are available.

Video band decided, what Tx power output would work best for my LOS application? I've seen 100mW up to over 1000mW.

On the FPV camera, what voltage should I get-- 5v or 12v? Or should I let the choice of Video Tx decide that? Or does it matter?

And then after I get these basic questions out of the way, I get to wade into the Quagmire of the Bells and Whistles of particular vid sytems...

Thanks,

--Bill
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At any rate, the above was a listing of my initial questions.

I've since decided using on these components::

5.8G 600mW Immersion 7-ch Tx
5.8G Immersion UNO 5800-V4 Rx

I'm wondering if I should spend a little extra on a diversity type of Rx? I'd only have 7" spacing at the base of the antennas on the Transmitter Tray, so antenna spacing would be minimal even in a "rabbit ear" configuration.

Next question:
I plan to use 3S Lipos attached to the Transmitter Tray for the Video RX and the monitor (a 5" monitor, same brand as the DPCAV 5" monitor). The monitor is listed at 7W, which is a draw of 600mA, no idea what the Rx will draw.

What _capacity_ batteries should I get? I have no clue as tohow many hours of runtime I'll be needin for each battery charge cycle. One hour? A couple of hours?

--Bill

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I'm wondering if I should spend a little extra on a diversity type of Rx? I'd only have 7" spacing at the base of the antennas on the Transmitter Tray, so antenna spacing would be minimal even in a "rabbit ear" configuration.

Diversity can provide a bit more performance while flying Quads but it is no longer essential with modern CP antennas. My opinion, others may disagree.

A spacing of 7" at 5.8GHz is parking lot length when compared to traditional VHF RF; it's more than enough spacing to do the job in traditional 5.8GHz spacial diversity. But most FPV'ers I see nowadays have a "diversity" configuration that uses a omni CP with a high gain CP helical or Patch. This configuration is best described as as a smart antenna switch rather than a spacial diversity setup.

What _capacity_ batteries should I get?

It's a simple math equation. Battery mAH capacity divided by mA current draw of the load will give you maximum (best case) run time in hours. Assuming you want roughly two hours run time with safety reserve, I estimate you'll need a 2200mAH battery.

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Good info.

This initial setup is going to be with an emphasis on portability so light weigh and simplicity is a plus. Even with a small monitor the TX Tray is starting ro bulk up a bit.

So "a couple of hours" is the target run time. I was thinking along that line, but didn't know if it was overkill or not. On just the aircraft TX alone, I don't recall how long I get out of a (700mAh) NiCad battery. I do carry a spare radio battery "just in case".

The 5" monitor is listed to pull 700mA. The Uno Rx is spec'd to pull 300mA, so I'd round that combined draw up to 1000mA. A 2200mAh Lipo would give a "couple of hours plus wiggle room", and 2200 mAh 3S 35C Lipos are a frequently-used flight battery with me. And once I need to get a "few spares" for the Video Rx system, I could get lower-cost Low-C batts.

--Bill

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